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Soil Investigation Work Plan Heritage Square Page 3 16— include the drilling of at least four small diameter boreholes adjacent to each tank. One borehole will be located near each tank end and two boreholes will be located on each side of the tank near the tank 4... center. Soil samples will be collected at approximately two feet below the bottom of each tank and at five-foot intervals thereafter to a depth of 10 feet below the deepest evidence of hydrocarbon contamination or thirty feet, whichever is greater. Two soil samples will be retained from each borehole for laboratory analyses. Soil samples will also be collected from beneath all underground piping located inside the Heritage Square building, ` Groundwater is anticipated at about 35 feet below grade therefore, if field evidence from any one borehole at a respective tank indicates soil contamination to 25 feet or more, one borehole will be advanced to the groundwater surface in the downgradient direction from the respective tank and a groundwater sample collected. The groundwater gradient direction will be estimated based on groundwater monitoring data from adjacent sites. Based on the findings from this scope of work, Condor may recommend additional investigation, remediation, or closure in-place of the USTs, as warranted. The disposition of the abandoned water well is not included in this Work Plan. 3.1 SITE PREPARATION Condor will complete a drilling permit application and obtain the required permit from the San Joaquin County Public Health Service, Environmcntal Health Department(SJCPHS,EHD)prior to the field work. If necessary, Condor will complete an encroachment permit application and obtain the permit from the City of Stockton Public Works Department. Condor will schedule and coordinate all field activities through the property owner. The proposed boring locations will be marked with white paint and USA will be notified at least 72 hours in advance of the fieldwork to locate and identify underground utilities in and near the work area. However, because companies contacted by USA may not identify utilities ` past private property lines and into the site, it is the responsibility of the property owner to identify site utilities. 3.2 GEOPROBE BOREHOLES The boreholes will be advanced using a Geoprobe" percussion hammer drive sampler equipped with a 1.75-inch O.D., 4-foot long, core barrel, fitted with a clean, single use, polyethylene liner. A licensed +� C57 drilling contractor will drill the boreholes under the supervision of a Condor geologist. The soil samples will be screened in the field with a photoionization detector(PID). Additional boreholes may be necessary if field data indicate that the proposed locations do not adequately delineate the extent of �.. contamination. Following completion of the sampling, the boreholes will be filled with neat cement containing 3-5% bentonite. The slurry will be tremied into the borehole to avoid bridging. �. 3.3 SOIL SAMPLING The soil retained inside each core barrel will be logged according to the Unified Soil Classification System. Geological logs will be prepared containing field observations including soil type, estimated moisture content, PID measurements, and the presence of staining or odor. Soil samples will be selected from the polyethylene liner at distinct changes in lithology and at intervals suggestive of soil contamination based on field screening. The soil samples will be retained, undisturbed, in the liners. CONDOR Y